Gas metal arc welding control method, welding condition setting method, welding control device, welding power source, welding system, program, gas metal arc welding method, and additive manufacturing method

Abstract

Provided is a method for controlling gas metal arc welding, with which it is possible to obtain an excellent weld bead shape regardless of the welding speed during the welding of a thin plate and to obtain optimal penetration performance according to the situation. A method for controlling gas metal arc welding in which, in gas metal arc welding using a shielding gas containing 30% or more of CO2 and using a thin plate as a material to be welded, feeding and welding current control are performed by switching a welding current to at least a current non-suppression period TIP or a current suppression period TIB, the present invention is provided with: a short-circuit time ratio determination step for determining the ratio of a short-circuit period to a predetermined time when there is one or more cycles including an arc period and a short-circuit period within the predetermined time; and a welding condition determination step for setting or correcting a welding condition such that the ratio of the short-circuit period determined in the short-circuit time ratio determination step is at least equal to or less than a predetermined threshold value, or equal to or less than a calculated threshold value, or a predetermined target value or a calculated target value.

Description

Technical Field

[0001] The present invention relates to a method for controlling the forward feeding period T of the welding wire. P and reverse feed period T N As one cycle, the arc welding control method, the control method of metal metal arc welding, the setting method of welding conditions, the welding control device, the welding power supply, the welding system, the program, the metal metal arc welding method and the additive manufacturing method are periodically repeated. Background Art

[0002] The welding of thin plates is used in the manufacturing of mass-produced products such as automobile parts. From the perspective of optimizing the production system to shorten welding time and save manpower, welding using welding robots and automatic welding equipment has become the mainstream. The welding method used in the welding of thin plates uses CO 2 The welding method generally uses 80% Ar-20% CO 2 There are two methods of gas MAG (Metal Active Gas) welding, but each method has its own advantages and disadvantages.

[0003] For example, CO 2 The welding is excellent in high-speed welding and energy-efficient. Furthermore, since stable penetration can be ensured and porosity defects are less likely to occur, it has the advantage of being applicable to the welding of galvanized steel sheets. On the other hand, if more spatter is generated or the welding speed is increased, the welding current needs to be increased. As a result, due to the influence of excess arc force, the penetration becomes deeper, so there is a disadvantage that burn-through is more likely to occur as the plate thickness decreases.

[0004] In addition, since MAG welding produces less spatter and a smaller penetration depth, it has the advantage of being able to suppress burn-through when the plate thickness is small, but on the other hand, it has the disadvantage of poor high-speed weldability. When the welding speed of MAG welding is increased, if the welding current is increased, the droplet transfer mode enters the spray transition area, so the arc extends beyond the molten pool width and cannot ensure sufficient penetration depth. In addition, in the welding of galvanized steel plates, there is a possibility of multiple porosity defects. In addition, MAG welding has a welding method using a pulse current (hereinafter also referred to as "pulse MAG welding"), which has the advantages of being able to further reduce spatter and deepen the penetration depth compared to MAG welding, but cannot ensure CO 2 The welding depth is not as deep as that of MAG welding, and the high-speed welding performance is poor. In addition, the disadvantage of galvanized steel sheet being easy to produce porosity defects is the same as that of MAG welding.

[0005] In this way, CO 2Welding and MAG welding each have their own advantages and disadvantages, but in recent years, there are also methods of applying feed speed control to these welding methods to compensate for the disadvantages of these welding methods.

[0006] For example, in the technology described in Patent Document 1, the pulse MAG welding has the problem that burn-through and deformation are likely to occur, and undercut is likely to occur when high-speed welding is performed. In order to solve this problem, Patent Document 1 discloses that forward feeding and reverse feeding are alternately performed, the forward feeding is to feed the welding wire as a consumable electrode in the direction of the welding object, and the reverse feeding is to feed the welding wire in the opposite direction to the forward feeding, the welding wire is periodically fed with a given cycle and amplitude, and a first heat input period consisting of a first heat input amount and a second heat input period consisting of a second heat input amount are periodically repeated. That is, the following is disclosed in Patent Document 1: the first heat input period and the second heat input period are respectively composed of a short circuit period and an arc period. When a short circuit is detected during the short circuit period of the second heat input period, the arc is extinguished by reducing the welding current after the short circuit in the second heat input period compared to the welding current during the arc period of the first heat input period. This maintains a stable arc and achieves low heat input, which can suppress burn-through of thin plate welding and improve the gap margin.

[0007] Prior Art Literature

[0008] Patent Literature

[0009] Patent Document 1: International Publication No. 2017 / 169899 Summary of the invention

[0010] -Problems to be solved by the invention-

[0011] However, the technology described in Patent Document 1 does not consider the appearance of the weld bead. As for the appearance of the weld bead, the wider the width of the weld bead, the flatter the shape, and the better the welding quality. However, the higher the welding speed, the more convex the weld bead shape tends to be. In particular, CO 2 The weld bead shape tends to be convex.

[0012] In addition, the technology described in Patent Document 1 has a low heat input, so the penetration is small, and pore defects are easily generated in the galvanized steel sheet. As described above, the welding of thin plates is applied in the field of mass production of products, and the optimization of the production system is required. Therefore, a welding method that can be universally applied regardless of the type of base material is desired.

[0013] Therefore, a technology is required that can achieve excellent weld bead appearance and optimal penetration performance according to the situation even when the welding speed is increased.

[0014] The present invention has been completed in view of the above-mentioned problems, and its purpose is to provide a control method for metal-metal arc welding, a method for setting welding conditions, a welding control device, a welding power supply, a welding system, a program, a metal-metal arc welding method and an additive manufacturing method, which can obtain an excellent weld bead shape and an optimal penetration performance corresponding to the conditions regardless of the welding speed in the welding of thin plates.

[0015] -Methods for solving the problem-

[0016] The above object of the present invention is achieved by the following structure [1] related to a method for controlling gas metal arc welding.

[0017] [1] A control method for metal-electrode gas shielded arc welding using a gas shielded arc welding system containing more than 30% CO 2 In the case of gas metal arc welding with thin plates as the welding material,

[0018] Based on at least the tip position of the welding wire or the feed speed signal, the welding current is switched to at least the current non-suppression period T IP Or the current suppression period T IB The feed and welding current control is performed so that during the forward feed period T P and reverse feed period T N The welding wire is fed toward the base material during the periodic switching of these periods.

[0019] The control method of the metal-electrode gas shielded arc welding is characterized by comprising:

[0020] a short circuit time ratio determining step of determining a ratio of the short circuit period to the predetermined time when there is one or more cycles including an arc period and a short circuit period within the predetermined time; and

[0021] The welding condition determination step sets or corrects welding conditions so that the ratio of the short circuit period determined in the short circuit time ratio determination step becomes at least a predetermined threshold value or a calculated threshold value, or a predetermined target value or a calculated target value.

[0022] Furthermore, the above-mentioned object of the present invention is achieved by the following structure [2] related to the method of setting welding conditions.

[0023] [2] A method for setting welding conditions when using a welding process including 30% or more CO 2 In the case of gas metal arc welding with thin plates as the welding material,

[0024] The welding current is switched to at least the current non-suppression period T based on at least the tip position of the welding wire or the feed speed signal. IP Or the current suppression period T IB The feed and welding current control is performed so that during the forward feed period T P and reverse feed period T N The welding wire is fed toward the base material during the periodic switching of these periods.

[0025] The method for setting welding conditions is characterized in that:

[0026] If there is one or more cycles including arc period and short circuit period within the predetermined time,

[0027] determining a ratio of the short circuit period to the predetermined time,

[0028] The welding conditions are set so that the determined ratio of the short-circuit period becomes at least a predetermined threshold value or a calculated threshold value or a predetermined target value or a calculated target value.

[0029] Furthermore, the above-mentioned object of the present invention is achieved by the following structure [3] involving a welding control device.

[0030] [3] A welding control device for use with a CO 2 In the case of gas metal arc welding with thin plates as the welding material,

[0031] The welding control device is used to switch the welding current to at least the current non-suppression period T based on at least the tip position of the welding wire or the feed speed signal. IP Or the current suppression period T IB The feed and welding current control is performed so that during the forward feed period T P and reverse feed period T N The welding wire is fed toward the base material during the periodic switching of these periods.

[0032] The welding control device is characterized by having:

[0033] a short circuit time ratio determination unit that determines a ratio of the short circuit period to the predetermined time when there is one or more cycles including an arc period and a short circuit period within the predetermined time; and

[0034] The welding condition determination unit sets or corrects welding conditions so that the ratio of the short circuit period determined by the short circuit time ratio determination unit becomes at least a predetermined threshold value or a calculated threshold value, or a predetermined target value or a calculated target value.

[0035] Furthermore, the above-mentioned object of the present invention is achieved by the following structure [4] involving a welding power source.

[0036] [4] A welding power source comprising the welding control device described in [3].

[0037] Furthermore, the above-mentioned object of the present invention is achieved by the following structure [5] involving the welding system.

[0038] [5] A welding system comprising the welding power source described in [4].

[0039] In addition, the above-mentioned object of the present invention is achieved by the following structure [6] involved in the program.

[0040] [6] A procedure in which a CO 2 In the case of gas metal arc welding with thin plates as the welding material,

[0041] The welding control device is used to switch the welding current to at least the current non-suppression period T based on at least the tip position of the welding wire or the feed speed signal. IP Or the current suppression period T IB The feed and welding current control is performed so that during the forward feed period T P and reverse feed period T N The welding wire is fed toward the base material during the periodic switching of these periods.

[0042] The invention is characterized in that a computer of a welding system having at least the welding control device is caused to execute a function having the following steps:

[0043] a short circuit time ratio determining step, in which, when there is one or more cycles including an arc period and a short circuit period within a predetermined time, the welding control device determines a ratio of the short circuit period to the predetermined time; and

[0044] The welding control device sets or corrects welding conditions so that the ratio of the short circuit period determined in the short circuit time ratio determination step becomes at least a predetermined threshold value or a calculated threshold value, or a predetermined target value or a calculated target value.

[0045] Furthermore, the above-mentioned object of the present invention is achieved by the following structure [7] involving a metal-electrode gas shielded arc welding method.

[0046] [7] A method of gas metal arc welding using a gas metal arc welding process comprising more than 30% CO 2 In the case of gas metal arc welding with thin plates as the welding material,

[0047] A control method for metal-electrode gas shielded arc welding is adopted, wherein the welding current is switched to at least a current non-suppression period T based on at least the front end position or feed speed signal of the welding wire. IP Or the current suppression period T IB The feed and welding current control is performed so that during the forward feed period T P and reverse feed period T N The welding wire is fed toward the base material during the periodic switching of these periods.

[0048] The gas metal arc welding method is characterized in that:

[0049] If there is one or more cycles including arc period and short circuit period within the predetermined time,

[0050] The welding conditions are set or corrected so that the ratio of the short-circuit period to the predetermined time becomes equal to or less than the value of the following formula (1) related to the feed speed setting value FW.

[0051] 0.007×FW+0.249 ・・・Formula (1)

[0052] In addition, the above-mentioned object of the present invention is achieved by the following structure [8] involving the additive manufacturing method.

[0053] [8] An additive manufacturing method using a material comprising more than 30% CO 2 Shielding gas, metal-shielded gas arc welding with thin plates as welding materials,

[0054] A control method for metal-electrode gas shielded arc welding is adopted, wherein the welding current is switched to at least a current non-suppression period T based on at least the front end position or feed speed signal of the welding wire. IP Or the current suppression period T IB The feed and welding current control is performed so that during the forward feed period T P and reverse feed period T N The welding wire is fed toward the base material during the periodic switching of these periods.

[0055] The additive manufacturing method is characterized in that

[0056] If there is one or more cycles including arc period and short circuit period within the predetermined time,

[0057] The welding conditions are set or corrected so that the ratio of the short-circuit period to the predetermined time becomes equal to or less than the value of the following formula (1) related to the feed speed setting value FW.

[0058] 0.007×FW+0.249 ・・・Formula (1)

[0059] -Effects of the Invention-

[0060] According to the present invention, in welding of thin plates, even under high-speed welding conditions, the weld bead shape is good and the optimum penetration according to the conditions can be ensured, thereby contributing to improvement of welding quality and optimization of production systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Figure 1 It is a schematic diagram showing a configuration example of a welding system according to the present embodiment.

[0062] Figure 2 This is a block diagram showing a schematic configuration of a power supply control unit in a welding power supply.

[0063] Figure 3 It is a waveform diagram illustrating the time variation of the wire feed speed.

[0064] Figure 4 This is a waveform diagram illustrating the temporal change in the position of the tip of the welding wire.

[0065] Figure 5 This is a flowchart for explaining an example of basic control of welding current in the present embodiment.

[0066] Figure 6 1 is a diagram showing a control example of the current setting signal Ir for designating the current value of the welding current.

[0067] Figure 7 This is a graph showing the relationship between the short circuit time ratio and the weld bead appearance (h / w).

[0068] Figure 8 This is a graph showing the relationship between the short circuit time ratio and the penetration performance (d / w).

[0069] Fig. 9 This is a graph showing the relationship between the short circuit time ratio and the weld bead appearance (h / w), which is a test result at an average feed speed of 7 m / min and a welding speed of 100 cm / min.

[0070] Fig.10 This is a graph showing the relationship between the short circuit time ratio and the penetration performance (d / w) in a test at an average feed speed of 7 m / min and a welding speed of 100 cm / min.

[0071] Fig.11 This is a flowchart for explaining the processing operations of the robot control device and the welding power source.

[0072] Fig.12 It is used to illustrate the welding current setting value I P1 The terminal position and welding current setting value I P2 A diagram showing the relationship between the terminal position setting, the wire feed speed, the wire tip position and the welding current setting value.

[0073] Fig.13 It is used to explain the current suppression period T IB A diagram showing the relationship between the terminal position setting, the wire feed speed, the wire tip position and the welding current setting value. DETAILED DESCRIPTION

[0074] Hereinafter, embodiments of the gas metal arc welding control method, welding condition setting method, welding control device, welding power supply, welding system, program, gas metal arc welding method and additive manufacturing method according to the present invention will be described in detail based on the accompanying drawings.

[0075] In addition, this embodiment is an example of a case where a welding robot is used, and the welding control method involved in the present invention is not limited to the structure of this embodiment. For example, the welding control method of the present invention can be applied to an automatic welding device using a trolley, or the welding control method of the present invention can be applied to a small mobile welding robot.

[0076] Furthermore, in the present embodiment, a gas metal arc welding (hereinafter also referred to as “GMAW”) method to which the welding control method according to the present invention is applied is described, but the welding control method according to the present invention can also be similarly applied to an additive manufacturing method to which gas metal arc welding is applied.

[0077] Here, the additive manufacturing technology that utilizes GMAW is useful in metal stacking modeling technology (WAAM: Wire and Arc Additive Manufacturing). In addition, the term additive manufacturing is sometimes used in a broad sense as the term stacking modeling or rapid prototyping, but in the present invention, the term additive manufacturing is used uniformly. When the method involved in the present invention is applied to additive manufacturing technology, "welding" is renamed "deposition", "additive manufacturing" or "stacking modeling". For example, when it is processed as welding, it becomes "welding conditions", but when the invention of this application is used as additive manufacturing, it is renamed "deposition conditions", and when it is processed as welding, it becomes a "welding system", but when the present invention is used as additive manufacturing, it can be renamed "additive manufacturing system".

[0078] <Overview of welding system>

[0079] Figure 1 This means that

[0080] The welding system 50 includes a welding robot 110 , a welding control device 120 , a feeding device (not shown) for feeding the welding wire 100 , a welding power source 140 , and a controller 150 .

[0081] The welding power source 140 is connected to the welding robot 110 via a positive power cable (not shown) so that the welding wire 100 as a consumable electrode can be energized, and is connected to the workpiece (hereinafter also referred to as "base material") 200 via a negative power cable (not shown). This connection is when welding is performed with reverse polarity. When welding is performed with positive polarity, the welding power source 140 can simply reverse the polarity.

[0082] Furthermore, a feeding device (not shown) for feeding welding wire 100 is connected to welding power source 140 via a signal line, and the feeding speed of the welding wire can be controlled.

[0083] The welding robot 110 is provided with a welding torch 111 as an end effector. The welding torch 111 has a power supply mechanism, that is, a welding tip, for supplying power to the welding wire 100. The welding wire 100 generates an arc from the front end by supplying power from the welding tip, and the heat is used to weld the workpiece 200 as a welding object. In addition, the welding tip is sometimes also generally referred to as a contact tip.

[0084] Furthermore, the welding torch 111 is provided with a shielding gas nozzle that is a mechanism for ejecting shielding gas. The shielding gas can be any gas composition that adopts a bead transition method based on the characteristics of the control used in the present embodiment. Specifically, it is preferred to include at least one gas of carbon dioxide, nitrogen, hydrogen, and oxygen with a high potential gradient. In addition, from the perspective of versatility, in the case of a mixed gas of argon gas (hereinafter also referred to as "Ar gas"), a system in which at least 30% by volume of carbon dioxide is mixed is more preferred, a system in which 90% by volume of carbon dioxide is mixed is further preferred, and carbon dioxide monomer is further preferred. In addition, the shielding gas is supplied from a shielding gas supply device not shown in the figure.

[0085] The welding wire 100 used in this embodiment is not particularly limited. For example, any one of a solid welding wire not including flux and a welding wire with flux including flux can be used. In addition, the material of the welding wire 100 is not limited. For example, the material can be mild steel, stainless steel, aluminum, titanium, and the surface of the welding wire can also be plated with Cu or the like. Furthermore, the diameter of the welding wire 100 is not particularly limited. In the case of this embodiment, it is preferred that the upper limit of the diameter is set to 1.6 mm and the lower limit is set to 0.8 mm.

[0086] In addition, in the present embodiment, the specific structure of the workpiece 200 is not particularly limited, and welding conditions such as the joint shape, welding posture, and groove shape are not particularly limited.

[0087] The welding control device 120 mainly controls the operation of the welding robot 110. The welding control device 120 holds training data that determines the operation mode, welding start position, welding end position, welding conditions, swinging operation, etc. of the welding robot 110 in advance, and instructs the welding robot 110 to control the operation of the welding robot 110. In addition, the welding control device 120 provides the welding conditions such as welding current, welding voltage, and feed speed in the welding operation to the welding power source 140 according to the training data.

[0088] In addition, if Figure 1 As shown, welding system 50 of the present embodiment is configured such that welding control device 120 and welding power source 140 are independent from each other. However, welding control device 120 may be provided in welding power source 140 .

[0089] The controller 150 is connected to the welding control device 120, and performs program creation or display for operating the welding robot 110, input of training data, etc., and provides the program to the welding control device 120. In addition, the controller 150 also has a function of manually operating the welding robot 110. In addition, the connection between the controller 150 and the welding control device 120 is not particularly limited to wired or wireless.

[0090] Welding power source 140 supplies power to welding wire 100 and workpiece 200 according to a command from welding control device 120, thereby generating an arc between welding wire 100 and workpiece 200. In addition, welding power source 140 outputs a signal for controlling the speed of feeding welding wire 100 to a feeding device (not shown) according to a command from welding control device 120.

[0091] <Functional structure of welding power source>

[0092] Next, refer to Figure 2 The functional configuration of welding power source 140 according to the present embodiment will be described in detail. Figure 2 1 is a block diagram showing a schematic configuration of a power supply control unit in welding power supply 140 .

[0093] The control system portion of the welding power source 140 is executed by, for example, the welding control device 120 or a computer (not shown) executing a program.

[0094] The control system of welding power source 140 includes current setting unit 36. Current setting unit 36 ​​in the present embodiment has a function of setting various current values ​​for regulating the welding current flowing through welding wire 100, a function of setting the start time and end time of the period in which the current value of the welding current is suppressed by current suppression period setting unit 36A, and a function of obtaining information on the position of the tip of welding wire 100 by welding wire tip position conversion unit 36B.

[0095] In addition, the current non-suppression period T described later IP Various condition settings, such as the rising interval T U , Decline interval T D The current setting point in the current setting unit 36 ​​is included in the function of setting various current values ​​for regulating the welding current.

[0096] In the case of the present embodiment, the welding current represents the current non-suppression period T alternately repeated based on the wire tip position. IP and current suppression period T IB In addition, the current setting unit 36 ​​sets the current non-suppression period T IP The set current value Ip (hereinafter also referred to as "peak current Ip") and the current suppression period T IBThe set current value Ib (hereinafter also referred to as "base current Ib") is set. In the case of this embodiment, the welding current is basically controlled by two values, the peak current Ip and the base current Ib. Therefore, the time t1 when the current value is suppressed starts indicates the time when the base current Ib starts, that is, the base current start time. In addition, the time t2 when the current value is suppressed ends indicates the time when the base current Ib ends, that is, the base current end time. In addition, the current non-suppression period T IP The start time is expressed as the peak current start time, and the current non-suppression period T IP The end time can also be expressed as the peak current end time.

[0097] The power supply main circuit of the welding power supply 140 is composed of a three-phase AC power supply (hereinafter also referred to as “AC power supply”) 1, a primary-side rectifier 2, a smoothing capacitor 3, a switching element 4, a transformer 5, a secondary-side rectifier 6, and a reactor 7.

[0098] The AC power input from the AC power source 1 is full-wave rectified by the primary-side rectifier 2, and then smoothed by the smoothing capacitor 3 to be converted into DC power. Next, the DC power is converted into high-frequency AC power by inverter control based on the switching element 4, and then converted into secondary-side power via the transformer 5. The AC output of the transformer 5 is full-wave rectified by the secondary-side rectifier 6, and then smoothed by the reactor 7. The output current of the reactor 7 is provided to the welding tip 8 as the output from the main circuit of the power source, and current is supplied to the welding wire 100 as a consumable electrode.

[0099] The welding wire 100 is fed by the feeding motor 24 and the feeding device 130, and the arc 9 is generated between the welding wire 100 and the base material 200. In the case of this embodiment, the feeding motor 24 feeds the welding wire 100 so that during the forward feeding period T during which the tip of the welding wire 100 moves toward the base material 200, the arc 9 is generated between the welding wire 100 and the base material 200. P and a reverse feeding period T during which the tip of welding wire 100 moves in a direction opposite to the direction in which base material 200 is located. N When set to 1 cycle, the forward feed period T is switched periodically. P and reverse feed period T N In addition, the "tip of the welding wire" mentioned here usually refers to the tip of the welding wire when the existence of the molten droplet hanging from the tip of the welding wire is ignored. That is, the welding wire melted by the arc is considered to be immediately transferred to the base material. As described later, its position is determined by the speed difference between the welding wire feeding speed and the melting speed of the welding wire.

[0100] Feeding of welding wire 100 by feed motor 24 is controlled by control signal Fc from feed drive unit 23. The average value of the feed speed is substantially the same as the melting speed. In the present embodiment, feeding of welding wire 100 by feed motor 24 is also controlled by welding power source 140.

[0101] The voltage setting unit 34 provides the current setting unit 36 ​​with a voltage setting signal Vr, which is a target value of the voltage applied between the welding tip 8 and the base material 200. The voltage setting signal Vr is also provided to the voltage comparison unit 35, and is compared with the voltage detection signal Vo detected by the voltage detection unit 32. In addition, the voltage detection signal Vo is an actual measurement value. The voltage comparison unit 35 amplifies the difference between the voltage setting signal Vr and the voltage detection signal Vo, and outputs it to the current setting unit 36 ​​as a voltage error amplification signal Va. The current setting unit 36 ​​controls the welding current so that the length of the arc 9 (hereinafter also referred to as "arc length") is constant. That is, the current setting unit 36 ​​performs constant voltage control by controlling the welding current.

[0102] The current setting unit 36 ​​resets the value of the peak current Ip, the value of the base current Ib, the period for providing the peak current Ip, or the value of the peak current Ip and the value of the base current Ib based on the voltage setting signal Vr and the voltage error amplification signal Va, and outputs the current setting signal Ir corresponding to the reset period or value to the current error amplification unit 37.

[0103] The current error amplifier 37 amplifies the difference between the current setting signal Ir provided as the target value and the current detection signal Io detected by the current detection unit 31, and outputs it as the current error amplification signal Ed to the inverter drive unit 30. The inverter drive unit 30 corrects the drive signal Ec of the switching element 4 according to the current error amplification signal Ed.

[0104] The current setting unit 36 ​​also receives a separation detection signal Dr1 which is a signal for detecting the separation of the molten droplet from the front end of the welding wire 100. The separation detection signal Dr1 is output from the separation detection unit 33. The separation detection unit 33 monitors the change of the voltage detection signal Vo output by the voltage detection unit 32, and detects the separation of the molten droplet from the welding wire 100 based on the change. The separation detection unit 33 is an example of a detection unit.

[0105] The detachment detection unit 33 detects the detachment of the droplet by, for example, comparing a value obtained by differentiating or second-order differentiating the voltage detection signal Vo with a detection threshold. The detection threshold is pre-stored in a storage unit (not shown). In addition, the detachment detection unit 33 may also generate a detachment detection signal Dr1 based on a change in a resistance value calculated from the voltage detection signal Vo and the current detection signal Io as actual measured values.

[0106] The average feed speed Favg of the fed welding wire 100 is also provided to the current setting unit 36. The average feed speed Favg is output by the average feed speed setting unit 20 based on the training data stored in the storage unit (not shown). That is, the average feed speed Favg can also be referred to as the set value (command value) of the feed speed.

[0107] The current setting unit 36 ​​determines the values ​​of the peak current Ip, the bottom current Ib, the time t1 when the bottom current Ib starts, and the time t2 when the bottom current Ib ends, based on the provided average feed speed Favg.

[0108] In this embodiment, if Figure 2 As shown in FIG. 1 , the average feed speed Favg is input to the current setting unit 36, but the signal input to the current setting unit 36 ​​may be replaced with the average feed speed Favg by using a value related to the average feed speed Favg as a setting value. For example, when a database of average feed speeds Favg and average current values ​​that can perform optimal welding at the average feed speed Favg is stored in a storage unit (not shown), the average current value may be replaced with the average feed speed Favg as a setting value.

[0109] The average feed speed Favg is also provided to the amplitude feed speed setting unit 21 and the feed speed command setting unit 22. The amplitude feed speed setting unit 21 here determines the values ​​of the amplitude Wf ​​and the period Tf based on the input average feed speed Favg. Amplitude feeding refers to a feeding method in which a period in which the feed speed is greater than the average feed speed Favg, that is, a forward feed period, and a period in which the feed speed is smaller than the average feed speed Favg, that is, a reverse feed period, alternately appear. In addition, a period in which the feed speed is smaller than the average feed speed Favg refers to a period in which the feed speed is smaller than the average feed speed Favg, including a negative feed speed, that is, a speed at which the tip of the welding wire moves in a direction opposite to the position of the base material 200. The amplitude Wf ​​provides a change range relative to the average feed speed Favg, and the period Tf provides a time of amplitude change as a repetition unit. The amplitude feed speed setting unit 21 generates and outputs an amplitude feed speed Ff corresponding to the determined values ​​of the amplitude Wf ​​and the period Tf or the frequency f.

[0110] The feed speed command setting unit 22 outputs a feed speed command signal Fw based on the amplitude feed speed Ff and the average feed speed Favg. In the present embodiment, the feed speed command signal Fw is expressed by the following equation.

[0111] Fw=Ff+Favg ・・・Formula (A)

[0112] In addition, the feed speed command setting unit 22 detects at which phase of the amplitude feed the detachment occurs based on the detachment detection signal Dr1 provided from the detachment detection unit 33. Among them, the feed speed command signal Fw represented by the formula (A) is limited to detecting the detachment of the molten droplet from the front end of the welding wire 100 within the assumed period. In the case where the detachment of the molten droplet is not detected within the assumed period, the feed speed command setting unit 22 may also switch the feed speed command signal Fw to a feed control based on a constant speed. For example, the feed speed command setting unit 22 switches the feed speed command signal Fw to a feed based on an average feed speed Favg. The switch from the feed based on the average feed speed Favg to the feed control represented by the formula (A) is determined according to the timing of detecting the detachment of the molten droplet.

[0113] The feed speed command signal Fw is output to the phase shift detection unit 26 , the feed error amplification unit 28 , and the current setting unit 36 ​​.

[0114] Feed error amplifier 28 amplifies the difference between feed speed command signal Fw as the target speed and feed speed detection signal Fo obtained by measuring the feed speed of welding wire 100 by feed motor 24, and outputs speed error amplified signal Fd after correcting the error amount to feed drive unit 23.

[0115] Feed drive unit 23 generates control signal Fc based on speed error amplified signal Fd and supplies it to feed motor 24. Feed speed converter 25 converts the rotation amount of feed motor 24 and the like into feed speed detection signal Fo of welding wire 100.

[0116] The phase shift detection unit 26 in this embodiment compares the feed speed command signal Fw with the feed speed detection signal Fo as a measured value, and outputs the phase shift time Tθd. Alternatively, the phase shift detection unit 26 may measure the feed action of the feed motor 24 when the parameters of the predetermined amplitude feed, such as the period Tf, the amplitude Wf, the average feed speed Favg, etc., are variable, and calculate the phase shift time Tθd.

[0117] Phase shift time Tθd is provided to wire tip position conversion unit 36B of current setting unit 36. Wire tip position conversion unit 36B calculates the tip position of welding wire 100 with base material 200 as a reference plane based on feed speed command signal Fw and phase shift time Tθd, and provides information on the calculated tip position to current suppression period setting unit 36A. Here, current suppression period setting unit 36A sets a period for suppressing the welding current, that is, a period for controlling current setting signal Ir to base current Ib, based on information on the tip position of welding wire 100, or based on information on the tip position of welding wire 100 and feed speed command signal Fw.

[0118] Current setting unit 36 ​​here is an example of a control unit that changes the welding current according to the position of the tip of welding wire 100 .

[0119] <Basic control of welding current based on information on the tip position of welding wire or feed speed command signal Fw>

[0120] Hereinafter, an example of controlling the welding current by welding power source 140 based on information on the tip position of welding wire 100 or feed speed command signal Fw will be described.

[0121] The welding current is controlled by the current setting unit 36 ​​constituting the welding power source 140. As described above, the current setting unit 36 ​​in the present embodiment realizes control by executing a program.

[0122] Current setting unit 36 ​​in the present embodiment controls the switching of the current value of the welding current based on the information of the tip position of welding wire 100 and feed speed command signal Fw of welding wire 100. Therefore, before describing the control of the welding current, the time change of feed speed command signal Fw and the time change of the tip position of welding wire 100 will be described.

[0123] Figure 3 This is a waveform diagram that illustrates the time variation of the feed speed command signal Fw. The horizontal axis is time (phase), and the vertical axis is the wire feed speed. The unit of the vertical axis is meters per minute or rotation speed. Figure 3 In the embodiment, the speed greater than the average feed speed Favg is expressed as "forward feed", and the speed less than the average feed speed Favg is expressed as "reverse feed". In the case of the present embodiment, the feed speed command signal Fw changes in a sinusoidal shape defined by the period Tf and the amplitude Wf, but is not particularly limited to the sinusoidal shape. In addition, hereinafter, the period when the feed speed is greater than the average feed speed Favg is referred to as the forward feed period T P On the contrary, the period during which the feed speed is lower than the average feed speed Favg is called the reverse feed period T N In addition, for the sake of convenience of explanation, the first half of each feeding period is referred to as the "early stage", and the second half is referred to as the "late stage".

[0124] Here, the average feed speed Favg can be regarded as the wire melting speed Fm.

[0125] Figure 4 This is a waveform diagram illustrating the temporal change in the tip position of welding wire 100 (hereinafter also referred to as “wire tip position”). The horizontal axis represents time (phase), and the vertical axis represents the distance (height) from the surface of base material 200 in the normal direction upward.

[0126] However, in Figure 4In FIG. 1 , the position (height) when welding wire 100 is fed at the maximum feed speed is taken as a reference distance, a distance greater than the reference distance is represented by a positive value, and a distance smaller than the reference distance is represented by a negative value.

[0127] exist Figure 4 In the figure, T0 and T4 represent the time points corresponding to the position where the tip of the welding wire 100 is closest to the surface of the base material (hereinafter also referred to as the "lowest end"), and T2 represents the time point corresponding to the position where the tip of the welding wire 100 is farthest from the surface of the base material (hereinafter also referred to as the "upper end") The vertex here is an example of the upper end.

[0128] like Figure 4 As shown in FIG. 1 , the period during which the front end position of the welding wire 100 approaches the surface of the base material over time, specifically, the period during which the front end position of the welding wire 100 moves from the uppermost end to the lowermost end is the “forward feed period T P The period during which the front end position of the welding wire 100 moves away from the surface of the base material over time, specifically, the period during which the front end position of the welding wire 100 moves from the lower end to the upper end is the "reverse feed period T N ”.

[0129] In addition, the time points corresponding to the reference distance are set as T1 and T3. T1 is a time point halfway from the bottom end where the tip of the welding wire 100 is closest to the surface of the base material to the top end where it is farthest. On the other hand, T3 is a time point halfway from the top end to the bottom end. Figure 4 As shown, the change width from the reference distance to the uppermost end, or the change width from the reference distance to the lowermost end is the "amplitude Wf", and the change width from the uppermost end to the lowermost end is the "wave height Wh".

[0130] In addition, please refer to Figure 3 as well as Figure 4 It can be seen that the feeding speed of welding wire 100 when the front end of welding wire 100 is located at the uppermost end or the lowermost end is the value of the predetermined average feeding speed Favg. Therefore, even if the welding wire feeding speed changes periodically, the melting speed of the welding wire and the feeding speed of the welding wire are balanced, the arc length is substantially constant, and stable welding can be continued.

[0131] Figure 5 This is a flowchart for explaining an example of basic control of welding current in the present embodiment. Figure 5 The control shown in Figure 2 The current setting unit 36 ​​described in the above description is executed. In addition, the symbol S in the figure represents a step. Figure 5 The control shown corresponds to a change in the tip position of welding wire 100 in one cycle. Figure 5, the state where time T is time point T0 is set as step 1. The current setting unit 36 ​​in this embodiment calculates the front end position of the welding wire 100 in order to control the current setting signal Ir. The average feed speed Favg is the same as the welding wire melting speed Fm. Therefore, if the difference between the feed speed command signal Fw and the welding wire melting speed Fm (≈Favg) is integrated, the front end position of the welding wire 100 can be obtained. Therefore, the current setting unit 36 ​​sets the front end position of the welding wire 100 based on the following formula.

[0132] Wire tip position = ∫ (Fw-Favg) dt ・・・Formula (B)

[0133] In addition, the change in the front end position calculated by equation (B) is Figure 4 correspond.

[0134] Among them, the feeding of the welding wire 100 is used in Figure 2 In the case of feed motor 24 described in the above, a phase shift may occur between the command and the actual feed speed, that is, feed speed detection signal Fo. Therefore, current setting unit 36 ​​corrects base current start time t1 calculated according to the tip position of welding wire 100 calculated based on average feed speed Favg and feed speed command signal Fw, based on phase shift time Tθd provided from phase shift detection unit 26. Specifically, the value of base current start time t1 is reset as shown in the following equation.

[0135] t1=t1+Tθd・・・Formula (C)

[0136] like Figure 6 As shown in FIG. 1 , the base current start time t1 represents the time T0 at which the tip of welding wire 100 is at the bottom, that is, the time T1 at which the tip of welding wire 100 is at the bottom, that is, the time T2 at which the tip of welding wire 100 is at the bottom, that is, the time T3 at which the welding wire 100 is at the forward feeding period, P Switch to reverse feed period T N In addition, at Figure 6 In the figure, t1' represents the maximum value of the base current starting time t1.

[0137] Here, return Figure 5 As shown in step 2, when the tip of the welding wire 100 reaches the bottom, i.e., time point T0, the current setting unit 36 ​​determines whether the time T measured from time point T0 is greater than the base current start time t1. During the period when the determination result of step 2 is negative (False), as shown in step 3, the current setting unit 36 ​​continues to output the peak current Ip as the current setting signal Ir. This period corresponds to Figure 6 The current non-suppression period T IP .

[0138] Next, if Figure 5As shown in FIG. 1 , when the result of the determination in step 2 is positive (True), as shown in step 4, the current setting unit 36 ​​starts to output the base current Ib as the current setting signal Ir. As described above, at the time when the switch to the base current Ib is started, the feeding of the welding wire 100 has already switched to the reverse feeding period T. N , the front end of the welding wire 100 begins to move away from the surface of the base material.

[0139] The molten droplet near the time point T0 when the tip of the welding wire 100 is at the bottom is located near the molten pool, so the arc length becomes shorter. N That is, the front end of the welding wire 100 is moved while being lifted. An inertial force acts on the growing molten droplet as a whole in the forward feeding direction, i.e., the direction approaching the base material 200. In contrast, the welding wire 100 moves in the opposite direction, i.e., the direction away from the base material 200. Therefore, the molten droplet further changes to a hanging shape, further promoting the detachment. In addition, the detachment of the molten droplet referred to in the present invention refers to either the transition of the molten droplet caused by short circuit or the transition of the molten droplet falling freely without short circuit (no short circuit) unless otherwise specified.

[0140] Furthermore, by switching the welding current value to the base current Ib during the period of predicted separation, the arc reaction force can be reduced compared to the period of supplying the peak current Ip. As a result, the force that lifts the droplet further weakens, and the droplet becomes more likely to be in a hanging shape. In this way, during the period of suppressing the welding current, i.e., the current suppression period T IB By separating the molten droplet from the tip of welding wire 100, even if a short circuit occurs, it is expected that spatter will be reduced.

[0141] Return again Figure 5 As shown in step 5, the current setting unit 36 ​​that switches the current setting signal Ir to the base current Ib determines whether the time T is longer than the base current end time t2. Figure 6 In FIG. 1 , t2′ represents the maximum value of the base current end time t2. While the result of the determination in step 5 is negative (False), as shown in step 4, the current setting unit 36 ​​outputs the base current Ib as the current setting signal Ir. After the supply of the base current Ib starts, the tip of the welding wire 100 moves so that it is lifted to the top, that is, the position where the tip is farthest from the base material 200, as the droplet detaches.

[0142] After the droplet is separated, in order to melt the welding wire 100 and form a droplet, it is necessary to end the supply period of the base current Ib, that is, the current suppression period T IB , switching to the period of supplying the peak current Ip, that is, the current non-suppression period T IPTherefore, it is preferable that the supply of the bottom current Ib is terminated during the period between the time points T1 and T2.

[0143] When the determination result of step 5 is positive (True), as shown in step 6, the current setting unit 36 ​​starts to output the peak current Ip as the current setting signal Ir. Next, as shown in step 7, the current setting unit 36 ​​determines whether the time T measured from the time point T0 becomes the time point T4. During the period when the determination result of step 7 is negative (False), as shown in step 6, the current setting unit 36 ​​outputs the peak current Ip as the current setting signal Ir. On the other hand, if the determination result of step 7 is positive (True), the current setting unit 36 ​​returns to step 1. Through the above control, the current setting signal Ir becomes a pulse waveform that periodically repeats the peak current Ip and the base current Ib.

[0144] The above description is the basic control of welding current by welding power source 140 based on information on the tip position of welding wire 100 or feed speed command signal Fw. The present inventors have repeatedly conducted intensive studies using this basic control and have found that the above-mentioned problems can be solved by setting or correcting the values ​​of various items of welding conditions based on the short-circuit time ratio, thereby completing the present invention.

[0145] Here, the short-circuit time ratio refers to the average value obtained by the ratio of a predetermined time to the total time of short circuits generated within the predetermined time. In the present embodiment, the calculation is performed when the cycle including the arc period and the short-circuit period is one or more within the predetermined time. On the other hand, if the short-circuit period is not included in the predetermined time, the short-circuit time ratio is regarded as zero. In addition, the predetermined time can be any fixed time, or it can be based on the cycle or frequency, but from the perspective of easy calculation, the time can be determined based on the frequency or the number of cycles. Hereinafter, unless otherwise specified, the short-circuit time ratio refers to the average value. In the present embodiment, the calculation is performed as a ratio of the total short-circuit time generated in about 3.1 seconds, which is 218 cycles at 70Hz. In addition, in the present embodiment, the short circuit is determined by the detection value of the arc voltage, and it is determined to be a short circuit when the detection value of the arc voltage is below 12V.

[0146] The short circuit period is the period from when the welding wire contacts the base material and the arc disappears to when the welding wire separates from the base material and the arc is generated, and the arc period is the period when the welding wire separates from the base material and the arc continues to be generated, that is, the period other than the short circuit period.

[0147] The relationship between the short-circuit time ratio and weld bead appearance and penetration performance using this basic control is shown in Figure 2. Figure 7 as well as Figure 8As shown, there is a tendency that the weld bead appearance becomes worse as the short circuit ratio increases, and there is a tendency that the penetration performance becomes lower. Figure 7 as well as Figure 8 The test results in Examples (see Tables 1-1 to 1-4) described later are shown, in which the average feed speed Favg is 7 m / min and the welding speed is 50 cm / min.

[0148] In the present embodiment, the bead appearance (hereinafter also referred to as "flatness of the bead") focuses on the flatness of the bead, and "h / w" which is the ratio of the bead height h to the bead width w is used as an index for evaluating the bead appearance. That is, the larger the h / w, the more convex the bead is, and the bead appearance is judged to be poor, and the smaller the h / w, the flatter the bead is, and the better the bead appearance is.

[0149] On the other hand, the penetration performance adopts "d / w" which is the ratio of the penetration depth d to the bead width w, and is used as an index for evaluating the penetration performance. That is, the larger the d / w is, the greater the penetration relative to the width, and thus the higher the penetration performance is judged to be, and the smaller the d / w is, the smaller the penetration relative to the width is, and thus the lower the penetration performance is judged to be.

[0150] By finding the above relationship, in this basic control method, the optimum short circuit time ratio is selected, and welding conditions that achieve the short circuit time ratio are set, or the short circuit time ratio is controlled and the welding conditions are corrected, thereby being able to adjust the depth of penetration to an appropriate level corresponding to the situation within a range where the weld bead appearance is good. For example, when using galvanized steel sheets, in order to increase the depth of penetration for the purpose of improving the porosity resistance, the welding conditions with a smaller short circuit time ratio may be set or corrected, and when welding thinner sheets, in order to reduce the depth of penetration, the welding conditions with a larger short circuit time ratio may be set or corrected.

[0151] The reason why the welding conditions can be set or corrected based on the short-circuit time ratio is that even when using CO 2 This basic control can also obtain good welding workability with gas. In the conventional welding method, such as MAG welding, even if short circuiting does not occur, sufficient penetration cannot be obtained, so it is impossible to adjust the penetration depth based on the short circuit time ratio as in the present invention. In addition, the conventional feed control technology is a technology with low heat input and short circuit center, so sufficient penetration cannot be obtained. Furthermore, the area with a small short circuit time ratio cannot obtain good welding workability as in this basic control, so it is out of the application range. For these reasons, the conventional feed control technology cannot adjust the penetration depth based on the short circuit time ratio.

[0152] In addition, the influence of the short-circuit time ratio tends to be different depending on the average feed speed Favg or the welding speed, so it is preferable to confirm the influence of the short-circuit time ratio for at least each average feed speed Favg. The lower the average feed speed Favg, the smaller the thermal energy used for melting, so the penetration performance becomes lower. In particular, the higher the welding speed, the more significant the tendency is, and sometimes the penetration depth changes with a certain short-circuit time ratio as the boundary.

[0153] In the present embodiment, when the average feed speed Favg is 7 m / min and the welding speed is 100 cm / min, the penetration depth tends to decrease extremely after the short circuit time ratio is around 0.300 (refer to Fig.10 ). In addition, referring to the test results in the embodiment described later with an average feed speed Favg = 7 m / min and a welding speed of 100 cm / min (see Tables 1-1 to 1-4), Fig. 9 as well as Fig.10 If the short circuit time ratio increases, there is a region of the short circuit time ratio where the balance between weld bead appearance and penetration performance cannot be achieved. Therefore, a threshold value can be set for the applied short circuit time ratio, and the welding conditions can be set or corrected so that it becomes below the threshold value. In addition, a target value can be set within a range below the threshold value, and the welding conditions can be set or corrected so that it becomes the target value.

[0154] In addition, the threshold value of the short circuit time ratio varies according to the welding information. The above description explains that the influence of the short circuit time ratio varies according to items of welding conditions such as the average feed speed Favg or the welding speed, but the amount of deposition related to the average feed speed Favg or the welding speed depends on items of welding conditions such as the welding wire used, the type of shielding gas, and the base material. Therefore, the threshold value or target value of the short circuit time ratio is preferably selected as an item of welding information from at least one of the welding wire (hereinafter also referred to as "welding material"), gas composition, wire diameter, plate thickness of the base material, feed speed setting value (=average feed speed Favg), and welding speed.

[0155] The "welding information" mentioned here refers to a group of information related to various conditions including welding conditions. In addition to welding conditions, for example, environmental conditions including information on items such as air temperature and humidity, and welding phenomenon quantities including geometric quantities such as sputtering and smoke quantity can be listed. In addition, gap, plate thickness, welding material, shielding gas type, base material, welding length, welding current, arc voltage, welding speed, shielding gas flow rate, various swing conditions (such as swing width, swing cycle, swing end stop time), etc. are examples of items constituting "welding conditions". Here, when explaining the items of welding information, it refers to the items of various conditions.

[0156] Based on the above, it is necessary to determine the range of the short circuit time ratio used in this basic control. The boundary of the short circuit time ratio is related to the welding information, so it is more preferable to find the short circuit time ratio that becomes the boundary based on the welding information. 2 When the welding speed is set to 50 cm / min on the normal speed side or 100 cm / min on the high speed side, the threshold of the short circuit time ratio is determined based on the average feed speed Favg. Specifically, the short circuit time ratio may be set to a value below the value of the following formula (1). In addition, in this embodiment, a welding speed of less than 80 cm / min is defined as a normal speed, and a welding speed of 80 cm / min or more is defined as a high speed.

[0157] The following formula (1) is at least when the welding wire is made of mild steel and the shielding gas is made of 100% CO 2 The calculation formula for the preferred threshold value is as follows: for example, when the welding wire is made of stainless steel and the shielding gas is made of 80% Ar gas + 20% CO 2 In the case of a mixed gas of gas, another calculation formula is used in the welding mode.

[0158] 0.007×Fw+0.249 ・・・Formula (1)

[0159] In addition, the threshold value or target value of the short circuit time ratio may be determined according to the application and the situation. For example, when the Favg of the above conditions is 7 m / min and the welding speed is 100 cm / min, the short circuit time ratio is determined to be within the range of 0.200 or less when processing a galvanized steel sheet, and the short circuit time ratio is determined to be within the range of 0.200 or more and 0.300 or less when processing a thinner sheet. Based on these threshold values ​​or target values ​​of the short circuit time ratio, the welding conditions are set or corrected.

[0160] <Setting method example>

[0161] Next, an example of a setting method of this embodiment will be described. Note that this setting method is just an example and is not limited to this.

[0162] An example of the setting method is shown below.

[0163] (a) In the present embodiment, experiments are conducted in advance under various welding conditions for each welding mode, the short circuit time ratio is calculated, and a threshold value or a target value of the short circuit time ratio is determined (short circuit time ratio determination step).

[0164] (b) Welding conditions are determined so that the short circuit time ratio is less than or equal to the threshold value or the target value. Alternatively, welding conditions are determined based on a database created for each welding mode so that the short circuit time ratio is less than or equal to the threshold value or the target value.

[0165] (c) When a database is used, a welding mode (at least welding wire and shielding gas) is selected, and if at least one item of welding information is input, other welding conditions are automatically initialized based on the database. For example, if the operator inputs the setting of feed speed and welding speed, welding current, arc voltage, etc. are automatically extracted and set. In addition, the database is preferably created by setting at least items of welding conditions such as frequency, amplitude, welding current setting value, arc voltage setting value, etc. for feed speed.

[0166] <Example of control method>

[0167] Next, based on Fig.11 A control method based on the short-circuit time ratio will be described. Fig.11 This is a flowchart for explaining the processing actions of the robot control device 120 and the welding power source 140. When starting arc welding, the operator operates the training pendant 150 provided in the robot control device 120 to input the applied training program and various setting values ​​to the robot control device 120, or automatically sets a part of the setting items by using the above-mentioned database. The training program here is defined as a trained program in which the actions of the welding robot 110 and the welding start and welding end instructions are trained in advance.

[0168] The robot control device 120 receives the training program and various setting value instructions in S1101.

[0169] In S1102, after the training program starts, the robot control device 120 moves the welding robot 110 to a predetermined welding start position and instructs the welding power source 140 to start welding (arc start). Alternatively, sensing may be performed before welding starts to correct the setting value of the training program.

[0170] In S1103, the welding power source 140 receives a welding start instruction from the robot control device 120. Then, the welding power source 140 controls a built-in power supply circuit (not shown) to supply power, thereby starting welding. Figure 1 ) and workpiece 200 (reference Figure 1 ) to generate an arc at the welding start point.

[0171] The robot control device 120 sends a control signal to the welding power source 140 or the welding robot 110 in S1104 to perform welding control. Welding control includes, for example, control of welding conditions, control of swinging motion, and welding line tracking control. In welding condition control, while the welding torch 111 is automatically moved in the welding direction, a signal for controlling at least one of the welding speed, feed speed, welding current, or arc voltage is sent to the welding robot 110, the welding power source 140, or a peripheral device such as a feeder to perform welding control.

[0172] The welding power source 140 is used in S1105. Figure 2 As described above, the welding current and feed are controlled. In addition, the welding power source 140 preferably has a calculation unit (in Figure 2 For example, Figure 2 The voltage detection unit 32 obtains the voltage detection signal Vo, and sets a short circuit counting unit (in Figure 2 (not shown in the figure), the result of the short-circuit counting unit is input into the calculation unit to calculate the short-circuit time ratio.

[0173] In addition, the short circuit counting unit determines that a short circuit occurs when the voltage detection signal Vo is lower than a threshold value of 12V, for example, and measures the short circuit time in S1106 and inputs it to the calculation unit. The calculation unit calculates the short circuit time (short circuit time / certain time) generated within a predetermined certain time as the short circuit time ratio. In addition, the short circuit counting unit and the calculation unit mentioned here do not need to be provided in the welding power supply, for example, they can be provided in the robot control device 120, or a control unit other than the robot control device 120 and the welding power supply 140, such as a PC, can be prepared to calculate the short circuit time ratio in the PC.

[0174] The welding power source 140 determines the calculated short-circuit time ratio in S1107. In addition, the determination unit that performs the determination does not need to be provided in the welding power source 140, and may be provided in the robot control device 120, for example, or in a control unit other than the robot control device 120 and the welding power source 140. The threshold value or target value used for determination may be a preset fixed value, or may be a value calculated based on welding information.

[0175] In the present embodiment, when the value is not below the threshold value or the target value, the correction amount of the welding condition can be calculated based on the calculated short circuit time ratio and the threshold value or the target value. Specifically, it is preferable to calculate the correction amount of the welding condition based on the difference between the calculated short circuit time ratio and the threshold value or the target value. In addition, in the present embodiment, the items of the welding condition for which the correction amount is calculated include the frequency when the forward feed period and the reverse feed period of the welding wire are set as one cycle, the amplitude during the forward feed and reverse feed of the welding wire, the welding current setting value during the current non-suppression period, the arc voltage setting value during the current non-suppression period, the welding current setting value during the current suppression period, the arc voltage setting value during the current suppression period, the welding wire position information at the end of the current non-suppression period, the welding wire position information at the end of the current suppression period, the ratio of the forward feed period to the reverse feed period, etc. It is more preferable to correct at least one of these items.

[0176] In S1108 , the robot controller 120 ends the welding (arc is turned off) based on the program.

[0177] In S1109 , the welding power source 140 receives a welding end (arc off) instruction from the robot controller 120 .

[0178] When the program ends, in S1110, robot controller 120 and welding power source 140 are stopped. When the program does not end, S1101 to S1110 are further repeated.

[0179] Furthermore, in this embodiment, the value of the frequency f, the peak current Ip, that is, the current non-suppression period T IP The set current, the base current Ib, that is, the current suppression period T IB The setting current and current non-suppression period T IP (Also called "peak current period"), current suppression period T IB (Also called "base current period"), forward feed period T P , reverse feed period T N Under each condition, the short circuit time ratio is determined, the weld appearance and welding workability become better, and it is easier to obtain the penetration depth.

[0180] In addition, the current non-suppression period T IP The set current or current suppression period T IB The setting current of is not limited to a fixed current value, and the setting value can be changed in each period. Therefore, as a representation of the current non-suppression period T IP Overall or current suppression period T IB An indicator of the overall thermal energy, using the current unsuppressed period T IPOr the current suppression period T IB The average current is expressed as the current non-suppression period T IP The average current is denoted as I P-AVG , the current suppression period T IB The average current is denoted as I B-AVG .

[0181] Hereinafter, each control element will be described in detail.

[0182] (Frequency f: 50~150Hz)

[0183] It is preferred to combine the forward feed period T P and reverse feed period T N The obtained period is regarded as one cycle, and the frequency f is fixed so that the molten drop formed at the tip of the welding wire is stably separated or dripped, thereby adjusting or controlling the short circuit time ratio. If the frequency is made variable, the weld bead appearance and the penetration depth may deviate due to the position relative to one welding length. The frequency f is preferably set in the range of 50 to 150 Hz as a condition for maintaining the penetration performance and forming the optimal molten drop size. In addition, it is more preferably 60 to 130 Hz, and even more preferably 70 to 120 Hz.

[0184] (Wave height Wh: 14-35% relative to the distance between the welding tip and the base material)

[0185] like Figure 4 As shown, the wave height Wh, which is the range of the change in the tip position of the welding wire 100 between the uppermost end and the lowermost end, is in the range of 14 to 35% relative to the distance between the welding tip and the base material. For example, when the distance between the welding tip and the base material is 25 mm, the wave height Wh should be set to a range of 3.5 mm to 8.75 mm. If the wave height Wh is in the range of 14 to 35% relative to the distance between the welding tip and the base material, the penetration performance can be ensured. In addition, the "reference distance" that becomes the reference position of the wave height Wh and the amplitude Wf ​​can be set arbitrarily.

[0186] The flatness of the weld bead contributes to the above-mentioned frequency and wave height Wh. In the present embodiment, these effects become significant, especially when the welding speed becomes high, and it is preferable to maintain a balance between a low frequency and a large wave height Wh. Specifically, the ratio of <frequency f / wave height Wh> is preferably in the range of 10.0 to 25.0.

[0187] In addition, in this embodiment, the current non-suppression period T IP And the current suppression period T IB The overall average welding current I AVG The current is preferably in the range of 150 to 300 A, and the current non-suppression period T IP And the current suppression period TIB The overall average arc voltage V AVG The arc stability is preferably 20 to 40 V. AVG and the average arc voltage V AVG That is, the average arc voltage V AVG With the average welding current I AVG Ratio of V AVG / I AVG Make a judgment, if V AVG / I AVG A range of 0.080 to 0.170 is more preferred, and good arc stability can be obtained.

[0188] The quality of the arc stability affects the flatness of the weld bead and the welding workability. In addition, as described above, the flatness of the weld bead also affects the frequency f and the wave height Wh. In the present embodiment, it was found that by setting or correcting various welding conditions so that the relationship between the value of (arc voltage) / (welding current) representing arc stability and the frequency f and the amplitude Wf ​​satisfies the following formula (2), it was found that better flatness of the weld bead can be obtained.

[0189] (Arc voltage) / (Welding current) ≥ 0.0237×(Frequency / Amplitude)-0.376 ・・・Formula (2)

[0190] (Current non-suppression period T IP Occupies the forward feed period T P 2 / 3 or more of the period)

[0191] The required current non-suppression period T IP The period of time during which the tip of the welding wire 100 moves from the uppermost end to the lowermost end is more than two-thirds of the period during which the tip of the welding wire 100 moves from the uppermost end to the lowermost end. P .

[0192] In the conventional short-circuit transfer method, the forward feed period T P The current non-suppression period T IP The ratio is controlled to be less than 1 / 2, and low sputtering welding can be performed. As a result, the arc pressure does not act on the molten pool, so the penetration becomes smaller.

[0193] In addition, if Fig.12 As shown, the current non-suppression period T IP It is preferable to divide the current suppression period T immediately after the base current changes to the predetermined current value. IB The subsequent rising interval T U , the current suppression period T that follows the change from the predetermined current value to the base current IBThe previous decline interval T D , and the rising interval T U And the descending interval T D Current control interval outside T C to control the current.

[0194] The rising interval T U For the purpose of adjusting the droplet size or promoting droplet detachment, it is preferable to adjust the current non-suppression period T IP The ratio of (rising interval T U / Current non-suppression period T IP )×100%” is less than 20%. In addition, the rising interval T U The welding current value can also be increased in the following way: Fig.12 In other words, the rising interval T U Relative to the current non-suppression period T IP The ratio is infinitely close to 0%.

[0195] In addition, the descending interval T D In order to adjust the droplet size before reverse feeding, it is preferable to adjust the current non-suppression period T IP The ratio of (the decreasing interval T D / Current non-suppression period T IP )×100%” is less than 20%. In addition, the falling interval T D The welding current value can also be reduced in the following way: Fig.12 The steep change shown, in other words, the falling interval T D Relative to the current non-suppression period T IP The ratio is infinitely close to 0%.

[0196] In addition, the rising interval T U , Decline interval T D The change may be in any of a linear shape, a curved shape or a step shape, or a combination thereof.

[0197] Next, if Fig.12 As shown, it is preferred that the current control interval T C At least two welding current setting values ​​are set in the embodiment. Here, the two welding current setting values ​​are set as the first welding current setting value I P1 and the second welding current setting value I P2 .

[0198] When the uppermost position of welding wire 100 is set to 0 degrees, the first welding current setting value I P1 The first welding current setting value I P1The end position of the range is set to a range below 20 degrees. By setting the first welding current setting value I P1 By setting the terminal position of the range to a range below 20 degrees, the swing of the molten droplet that is initially formed can be suppressed, and a more stable detachment can be maintained.

[0199] In addition, when the uppermost end position of welding wire 100 is set to 0 degrees as a reference, the second welding current setting value I P2 The second welding current setting value I P2 The end position of the range is set to be in the range of 135 to 220 degrees. P2 The terminal position of the range is set in the range of 135 to 220 degrees, which can make the arc pressure act effectively on the molten pool, and even if the short-circuit time ratio becomes large, a stable penetration depth can be obtained.

[0200] Furthermore, if Fig.13 As shown, when the welding current setting value I P2 The end of the range is set as the current control interval T C terminal, set the welding current to I P2 When the terminal position of the range is set to Xdeg, it is preferable to set the current suppression period T IB The terminal position is set within the range of (X+100) to (X+220) degrees. IB The terminal position is set in the range of (X+100) to (X+220) degrees. During the current suppression period T IB The timing when the inertial force acts at the maximum is included, and therefore it is preferable from the viewpoint of stabilizing the droplet separation.

[0201] At the first welding current setting value I P1 The welding current set in the range of 250 to 600 A is preferably set in the range of 250 to 600 A. P2 The welding current set in is preferably in the range of 300 to 650 A. By setting the first welding current setting value I P1 and the second welding current setting value I P2 The setting current is set to the above range, which can further improve the welding current setting value I P1 and the second welding current setting value I P2 And the effect obtained.

[0202] In addition, at the second welding current setting value I P2 The welding current set in the first welding current setting value I P1 The larger the welding current is set.

[0203] Preferably in the current control interval T C Specifically, at the first welding current setting value I P1 and the second welding current setting value I P2 During the period, the external characteristics of the welding power source 140 are set. More specifically, by setting the external characteristics of the welding power source 140 within the range of 0.05V to 20V / 100A, the welding current changes even when the protrusion length changes during welding, thereby controlling the arc length to be substantially constant.

[0204] From the viewpoint of adjusting the droplet size, it is preferable that the current non-suppression period T IP The average current I P-AVG The current suppression period T IB The average current I B-AVG The current non-suppression period T is preferably 80 to 150 A from the viewpoint of adjusting the droplet size. IP The current suppression period T IB The range is 2.0 to 9.0 ms.

[0205] Example

[0206] The present invention will be described in more detail below with reference to Examples. The present invention is not limited to these Examples, and modifications can be made within the scope of the gist of the present invention, and all of these modifications are included in the technical scope of the present invention.

[0207] <Common welding conditions>

[0208] The common welding conditions are as follows.

[0209] Welding wire: Mild steel solid wire

[0210] Protective gas: 100% CO 2

[0211] Base material: SS400 (rolled steel for general structure JIS G 3101: 2004)

[0212] Welding technique: cladding plate

[0213] Welding wire welding speed 50cm / min (normal speed) or 100cm / min (high speed)

[0214] Feed speed setting value (= average feed speed Favg): 7~10m / min (7, 8, 9, 10m / min)

[0215] <Evaluation Method>

[0216] The flatness and penetration performance of the weld bead were evaluated as follows, and a comprehensive evaluation was performed.

[0217] As described above, the flatness of the weld bead is determined by the ratio "h / w" of the weld bead height h to the weld bead width w. In addition, the case where h / w is 0.35 or less is A (optimal), the case where it exceeds 0.35 and is 0.40 or less is B (excellent), the case where it exceeds 0.40 and is 0.50 or less is C (good), the case where it exceeds 0.50 and is 0.60 or less is D (acceptable), and the case where it is 0.60 or more is E (unacceptable).

[0218] The penetration performance is determined by the ratio of the penetration depth d to the bead width w, "d / w". In addition, the case where d / w is 0.35 or more is A (excellent), the case where it is less than 0.35 and 0.30 or more is B (good), the case where it is less than 0.30 and 0.28 or more is C (acceptable), and the case where it is less than 0.28 is D (unacceptable).

[0219] Next, the comprehensive evaluation of the flatness and penetration performance of the weld bead is as follows.

[0220] Comprehensive evaluation A (optimal): When both h / w and d / w are A

[0221] Comprehensive evaluation B (excellent): h / w and d / w are a combination of A and B

[0222] Comprehensive evaluation C (good): h / w is B to C, d / w is a combination of B to C, or a combination of A and C

[0223] Comprehensive D evaluation (pass): h / w is D

[0224] Comprehensive evaluation E (unqualified): h / w is E or d / w is D

[0225] The test results are shown in Tables 1-1 to 4-4 together with the welding conditions other than the common test conditions. In addition, Tables 1-1 to 1-4 show the test results at a feed rate of 7 m / min, Tables 2-1 to 2-4 show the test results at a feed rate of 8 m / min, Tables 3-1 to 3-4 show the test results at a feed rate of 9 m / min, and Tables 4-1 to 4-4 show the test results at a feed rate of 10 m / min.

[0226] [Table 1-1]

[0227]

[0228] [Table 1-2]

[0229]

[0230] [Table 1-3]

[0231]

[0232] [Table 1-4]

[0233]

[0234] First, Tables 1-1 to 1-4, which are test results at a feed speed of 7 m / min, will be described.

[0235] As shown in Tables 1-1 to 1-4, the short-circuit time ratios of test numbers No. 5, No. 28, No. 29, No. 30, No. 46, and No. 47 all exceeded the threshold value 1 obtained by formula (1), so d / w was less than 0.28, that is, the penetration depth became shallow and the evaluation was D. As a result, the comprehensive evaluation was an unacceptable evaluation of E.

[0236] The short circuit time ratio and arc voltage / welding current values ​​of the other tests all satisfied threshold 1 and threshold 2 obtained by formula (2). Therefore, the d / w evaluation became C, B, and A evaluations respectively from the group with a short circuit time ratio close to threshold 1, and the h / w evaluation tended to become A, B, C, and D evaluations respectively from the group with a large arc voltage / welding current.

[0237] In particular, the d / w evaluation and h / w ​​evaluation of test numbers No. 10, No. 11, No. 16 to 19, No. 22, No. 23, No. 32, No. 33, No. 38 to No. 41, and No. 43 were all A evaluations, and as a result, the comprehensive evaluation also became the highest A evaluation.

[0238] In addition, the tests other than the comprehensive evaluations A and E were respectively comprehensively evaluated as B and C based on the above-mentioned criteria.

[0239] Next, Tables 2-1 to 2-4, which are test results at a feed rate of 8 m / min, are described.

[0240] [Table 2-1]

[0241]

[0242] [Table 2-2]

[0243]

[0244] [Table 2-3]

[0245]

[0246] [Table 2-4]

[0247]

[0248] As shown in Tables 2-1 to 2-4, for test No. 75, the arc voltage / welding current value was below threshold 2, so the h / w evaluation was D, but the d / w evaluation was A, so the overall evaluation was D, which was the lowest passing line.

[0249] The short circuit time ratio and arc voltage / welding current values ​​of the other tests all satisfy threshold 1 and threshold 2, so the d / w evaluation becomes B and A respectively starting from the group with a short circuit time ratio close to threshold 1, and the h / w evaluation becomes A, B, and D respectively starting from the group with a large arc voltage / welding current.

[0250] In particular, the d / w evaluation and h / w ​​evaluation of test numbers No. 56 to No. 59, No. 64 to No. 71, No. 73 to No. 74, No. 79 to No. 81, No. 83 to No. 88, No. 90, and No. 92 were all A evaluations, and as a result, the comprehensive evaluation was also the highest A evaluation.

[0251] In addition, the tests other than the comprehensive evaluations A and D were respectively comprehensively evaluated as B and C based on the above-mentioned criteria.

[0252] Next, Tables 3-1 to 3-4 showing the test results when the feed speed is 9 m / min are described.

[0253] [Table 3-1]

[0254]

[0255] [Table 3-2]

[0256]

[0257] [Table 3-3]

[0258]

[0259] [Table 3-4]

[0260]

[0261] As shown in Tables 3-1 to 3-4, the short circuit time ratio of test No. 122 was greater than the threshold value 1, so the d / w evaluation was D, and the overall evaluation was E, which was unacceptable. In addition, in test Nos. 120, 124, and 128, the arc voltage / welding current was less than the threshold value 2, so the h / w evaluation was D, but the d / w evaluation was A, so the overall evaluation was D, which was the pass line.

[0262] In all other tests, the short circuit time ratio and arc voltage / welding current values ​​satisfied threshold 1 and threshold 2, so the d / w evaluation became C, B, and A respectively starting from the group where the short circuit time ratio was close to threshold 1, and the h / w evaluation became A, B, and C respectively starting from the group where the arc voltage / welding current was large as a tendency.

[0263] In particular, the d / w evaluation and h / w ​​evaluation of test numbers No. 101, No. 102, No. 105, No. 106, No. 110 to No. 113, No. 125, No. 130, No. 133, and No. 136 to No. 140 were all A evaluations, and as a result, the comprehensive evaluation also became the highest A evaluation.

[0264] Next, Tables 4-1 to 4-4, which are test results at a feed speed of 10 m / min, are described.

[0265] [Table 4-1]

[0266]

[0267] [Table 4-2]

[0268]

[0269] [Table 4-3]

[0270]

[0271] [Table 4-4]

[0272]

[0273] As shown in Tables 4-1 to 4-4, the short-circuit time ratios of test numbers No. 168, No. 191, and No. 192 exceeded the threshold value 1, so the d / w evaluation became a D evaluation, and as a result, the comprehensive evaluation also became an unqualified E evaluation. In addition, in test number No. 172, since the arc voltage / welding current value was less than the threshold value 2, the h / w evaluation was a D evaluation, but the d / w evaluation was an A evaluation, so the comprehensive evaluation was a D evaluation on the qualified line.

[0274] In all other tests, the short circuit time ratio and arc voltage / welding current values ​​satisfy threshold 1 and threshold 2, so the d / w evaluation becomes A and B evaluations respectively starting from the group with a short circuit time ratio close to threshold 1, and the h / w evaluation becomes B and C evaluations respectively starting from the group with a large arc voltage / welding current.

[0275] In particular, the d / w evaluation and h / w ​​evaluation of test numbers No. 149, No. 150, No. 153, No. 158, No. 162, and No. 190 were all A evaluations, and as a result, the comprehensive evaluation was also the highest A evaluation.

[0276] In addition, the present invention is not limited to the above-mentioned embodiment and each example, and modifications, improvements, etc. can be made as appropriate.

[0277] As described above, the following matters are disclosed in this specification.

[0278] (1) A method for controlling metal-electrode gas shielded arc welding using a gas arc welding system containing more than 30% CO 2 In the case of gas metal arc welding with thin plates as the welding material,

[0279] Based on at least the tip position of the welding wire or the feed speed signal, the welding current is switched to at least the current non-suppression period T IP Or the current suppression period T IB The feed and welding current control is performed so that during the forward feed period T P and reverse feed period T N The welding wire is fed toward the base material during the periodic switching of these periods.

[0280] The control method of the metal-electrode gas shielded arc welding is characterized by comprising:

[0281] a short circuit time ratio determining step of determining a ratio of the short circuit period to the predetermined time when there is one or more cycles including an arc period and a short circuit period within the predetermined time; and

[0282] The welding condition determination step sets or corrects welding conditions so that the ratio of the short circuit period determined in the short circuit time ratio determination step is at least equal to or less than a predetermined threshold value or a calculated threshold value, or a predetermined target value or a calculated target value.

[0283] According to this configuration, in welding of thin plates, an excellent weld bead shape and optimum penetration performance according to the conditions can be obtained regardless of the welding speed.

[0284] (2) The method for controlling gas metal arc welding according to (1), characterized in that:

[0285] The method comprises the step of determining the threshold value or the target value based on a predetermined item of welding information,

[0286] The item of the welding information is selected from at least one of a welding wire type, a gas composition, a welding wire diameter, a plate thickness, a feed speed setting value FW, and a welding speed.

[0287] According to this configuration, the threshold value or target value of the short circuit period ratio can be determined based on at least one of the wire type, gas composition, wire diameter, plate thickness, feed speed setting value FW, and welding speed.

[0288] (3) The method for controlling gas metal arc welding according to (2), characterized in that:

[0289] When determining the threshold value, the threshold value is calculated based on at least the following formula (1) related to the feed speed setting value FW.

[0290] 0.007×FW+0.249 ・・・Formula (1)

[0291] According to this configuration, the threshold value of the short-circuit period ratio can be obtained based on the equation (1) related to the feed speed setting value Fw.

[0292] (4) The method for controlling gas metal arc welding according to any one of (1) to (3), wherein in the welding condition determination step,

[0293] As the welding condition items, at least the frequency f of the one cycle, the amplitude Wf ​​of the forward feed or reverse feed of the welding wire, the welding current, and the arc voltage are set.

[0294] Set the welding speed to high speed welding above 80cm / min.

[0295] In this case,

[0296] The welding conditions are set or corrected so that the set value or the detected value of the frequency f, the amplitude Wf, the welding current, and the arc voltage satisfies the following formula (2).

[0297] (Arc voltage) / (Welding current) ≥ 0.0237×(Frequency / Amplitude)-0.376 ・・・Formula (2)

[0298] According to this configuration, in the case of high-speed welding at a welding speed of 80 cm / min or more, by setting or correcting various welding conditions so that the value of arc voltage / welding current becomes equal to or greater than 0.0237×(frequency / amplitude)-0.376, (arc voltage) / (welding current) can be determined, thereby obtaining an excellent weld bead shape.

[0299] (5) The method for controlling gas metal arc welding according to (4), characterized in that:

[0300] The welding conditions are set or modified so that

[0301] The setting value or detection value of the frequency f is in the range of 50 to 150,

[0302] The setting value or detection value of the amplitude Wf ​​is in the range of 3.0 to 8.75, and

[0303] The frequency f / the amplitude Wf ​​satisfies 10-25.

[0304] According to this configuration, by setting or correcting the frequency setting value or detection value to a range of 50 to 150 and the amplitude setting value or detection value to a range of 3.0 to 8.75 and frequency / amplitude satisfying 10 to 25, better bead flatness can be obtained.

[0305] (6) The method for controlling gas metal arc welding according to (4) or (5), characterized in that the set value or the detected value of the welding current or the arc voltage uses an average value, respectively, and the welding conditions are set or corrected so that (arc voltage) / (welding current) satisfies 0.05V to 20V / 100A.

[0306] According to this configuration, by setting or correcting (arc voltage) / (welding current) to satisfy 0.05 V to 20 V / 100 A, better flatness of the weld bead can be obtained.

[0307] (7) The method for controlling gas metal arc welding according to any one of (1) to (6), characterized in that:

[0308] In the welding condition determination step,

[0309] As the welding condition to be set or modified,

[0310] During the current non-suppression period T IP There are at least two welding current setting values ​​I P1 ,I P2 ,

[0311] During the forward feed period TP , with the position of the welding wire at which the feed speed is set as a reference and set to 0 degrees,

[0312] In this case,

[0313] Set or modify the welding current setting value I within the range of 20 degrees or less P1 The end position of the range,

[0314] Set or modify the welding current setting value I within the range of 135 to 220 degrees P2 The end position of the range.

[0315] According to this configuration, by setting the first welding current setting value I P1 The end position of the range is set to a range below 20 degrees, which can suppress the swing of the initially formed droplet and maintain a more stable separation. P2 The terminal position of the range is set in the range of 135 to 220 degrees, which can make the arc pressure act effectively on the molten pool and obtain a stable penetration depth.

[0316] (8) The method for controlling gas metal arc welding according to (7), characterized in that:

[0317] As the welding condition to be set or modified,

[0318] The welding current setting value I P2 The end of the range is set as the current non-suppression period T IP The terminal,

[0319] The welding current setting value I P2 The end position of the range is set to Xdeg,

[0320] In this case,

[0321] The current suppression period T is set or modified within the range of (X+100) to (X+220) degrees. IB terminal position.

[0322] According to this configuration, since during the current suppression period T IB The timing when the inertial force is at its maximum is included, so the droplet separation can be stabilized.

[0323] (9) The method for controlling gas metal arc welding according to (7) or (8), characterized in that:

[0324] The welding current setting value I P1The setting current is set to 300-600A, and the welding current setting value I P1 The setting voltage is set to 20~45V,

[0325] The welding current setting value I P2 The setting current is set to 350-650A, and the welding current setting value I P2 The set voltage is set to 20~50V.

[0326] According to this configuration, the current value of the first welding current setting value I can be further increased. P1 and the second welding current setting value I P2 And the effect obtained.

[0327] (10) The method for controlling gas metal arc welding according to any one of (1) to (9), characterized in that:

[0328] The feed and welding current control are controlled so that the current non-suppression period T IP The forward feed period T P for more than 2 / 3 of the period.

[0329] According to this configuration, in welding of thin plates by an arc welding method in which forward feeding and reverse feeding of the tip of the welding wire are periodically repeated, both stable penetration depth and reduction of spatter can be achieved.

[0330] (11) The method for controlling gas metal arc welding according to any one of (1) to (10), characterized in that:

[0331] A database is provided, wherein for each item of welding information selected from at least one of welding wire type, gas composition, welding wire diameter, plate thickness, feed speed setting value, and welding speed, the ratio of the short circuit period is associated with the item of the welding condition,

[0332] In the welding condition determination step, the welding condition is determined based on the items of the welding information input in advance and the database, and the welding condition is set or corrected.

[0333] According to this configuration, welding conditions are determined and set or corrected based on items of welding information input in advance and a database, thereby determining an appropriate threshold value of the short circuit time ratio, and achieving both stable penetration depth and spatter reduction in welding of thin plates.

[0334] (12) The method for controlling gas metal arc welding according to (11), wherein the welding condition items include at least one of the following items:

[0335] The forward feeding period T of the welding wire P and reverse feed period T N Set the frequency f to 1 cycle;

[0336] The amplitude Wf ​​of the welding wire during forward feeding or reverse feeding;

[0337] The current non-suppression period T IP The welding current setting value;

[0338] The current non-suppression period T IP Arc voltage setting value;

[0339] The current suppression period T IB The welding current setting value;

[0340] The current suppression period T IB Arc voltage setting value;

[0341] End the current non-suppression period T IP The welding wire position information (Deg5);

[0342] welding wire position information (Deg Ta1) at the end of the current suppression period; and

[0343] The forward feeding period T P During the reverse feed period T N ratio (PFR).

[0344] According to this configuration, an appropriate threshold value of the short-circuit time ratio can be determined in accordance with welding conditions, and both stable penetration depth and reduction of spatter can be achieved in welding of thin plates.

[0345] (13) The method for controlling gas metal arc welding according to (11) or (12), characterized in that:

[0346] The method comprises at least detecting arc voltage during welding,

[0347] In the short circuit time ratio determination step, based on the detected value of the arc voltage, a period during which the voltage is equal to or less than a predetermined voltage value is calculated as the short circuit period, and based on the calculated short circuit period, the short circuit time ratio is determined.

[0348] In the welding condition determination step, the welding condition is corrected so that the short circuit time ratio becomes at least a predetermined threshold value or a calculated threshold value or a predetermined target value or a calculated target value.

[0349] According to this configuration, the short-circuit period can be calculated based on the detected value of the arc voltage, and the short-circuit time ratio can be determined based on the calculated short-circuit period.

[0350] (14) A method for controlling metal-electrode gas shielded arc welding using a gas arc welding furnace containing more than 30% CO 2 In the case of gas metal arc welding with thin plates as the welding material,

[0351] The welding current is switched to at least the current non-suppression period T based on at least the tip position of the welding wire or the feed speed signal. IP Or the current suppression period T IB The feed and welding current control is performed so that during the forward feed period T P and reverse feed period T N The welding wire is fed toward the base material during the periodic switching of these periods.

[0352] The method for setting welding conditions is characterized in that:

[0353] If there is one or more cycles including an arc period and a short circuit period within a predetermined time,

[0354] determining a ratio of the short circuit period to the predetermined time,

[0355] The welding conditions are set so that the determined ratio of the short-circuit period becomes at least a predetermined threshold value or a calculated threshold value or a predetermined target value or a calculated target value.

[0356] According to this configuration, in welding of thin plates, an excellent weld bead shape and optimum penetration performance according to the conditions can be obtained regardless of the welding speed.

[0357] (15) A welding control device for use with a welding machine containing 30% or more CO 2 In the case of gas metal arc welding with thin plates as the welding material,

[0358] The welding current is switched to at least the current non-suppression period T based on at least the tip position of the welding wire or the feed speed signal. IP Or the current suppression period T IB The feed and welding current control is performed so that during the forward feed period T P and reverse feed period T N The welding wire is fed toward the base material during the periodic switching of these periods.

[0359] The welding control device is characterized by having:

[0360] a short circuit time ratio determination unit that determines a ratio of the short circuit period to the predetermined time when there is one or more cycles including an arc period and a short circuit period within the predetermined time; and

[0361] The welding condition determination unit sets or corrects welding conditions so that the ratio of the short circuit period determined by the short circuit time ratio determination unit becomes at least a predetermined threshold value or a calculated threshold value or a predetermined target value or a calculated target value.

[0362] According to this configuration, in welding of thin plates, an excellent weld bead shape and optimum penetration performance according to the conditions can be obtained regardless of the welding speed.

[0363] (16) A welding power source comprising the welding control device described in (15).

[0364] According to this configuration, in welding of thin plates, an excellent weld bead shape and optimum penetration performance according to the conditions can be obtained regardless of the welding speed.

[0365] (17) A welding system comprising the welding power source described in (16).

[0366] According to this configuration, in welding of thin plates, an excellent weld bead shape and optimum penetration performance according to the conditions can be obtained regardless of the welding speed.

[0367] (18) A procedure in which the use of a process comprising more than 30% CO 2 In the case of gas metal arc welding with thin plates as the welding material,

[0368] The welding control device is used to switch the welding current to at least the current non-suppression period T based on at least the tip position of the welding wire or the feed speed signal. IP Or the current suppression period T IB The feed and welding current control is performed so that during the forward feed period T P and reverse feed period T N The welding wire is fed toward the base material at the same time as the periodic switching of these periods.

[0369] The invention is characterized in that a computer of a welding system having at least the welding control device is caused to execute a function having the following steps:

[0370] a short circuit time ratio determining step, in which, when there is one or more cycles including an arc period and a short circuit period within a predetermined time, the welding control device determines a ratio of the short circuit period to the predetermined time; and

[0371] The welding control device sets or corrects welding conditions so that the ratio of the short circuit period determined in the short circuit time ratio determination step becomes at least a predetermined threshold value or a calculated threshold value, or a predetermined target value or a calculated target value.

[0372] According to this configuration, in welding of thin plates, an excellent weld bead shape and optimum penetration performance according to the conditions can be obtained regardless of the welding speed.

[0373] (19) A method for controlling gas metal arc welding using a shielding gas containing 30% or more of CO2 and a thin plate as a material to be welded, wherein:

[0374] The welding current is switched to at least the current non-suppression period T based on at least the tip position of the welding wire or the feed speed signal. IP Or the current suppression period T IB The feed and welding current control is performed so that during the forward feed period T P and reverse feed period T N As these periodic switchings are performed, the front end of the welding wire is fed toward the base material.

[0375] The gas metal arc welding method is characterized in that:

[0376] If there is one or more cycles including an arc period and a short circuit period within a predetermined time,

[0377] The welding conditions are set or corrected so that the ratio of the short-circuit period to the predetermined time becomes equal to or less than the value of the following formula (1) related to the feed speed setting value FW.

[0378] 0.007×FW+0.249 ・・・Formula (1)

[0379] According to this configuration, in welding of thin plates, an excellent weld bead shape and optimum penetration performance according to the conditions can be obtained regardless of the welding speed.

[0380] (20) An additive manufacturing method using a material comprising more than 30% CO 2 Shielding gas, metal-shielded gas arc welding with thin plates as welding materials,

[0381] The additive manufacturing method adopts a control method for metal-electrode gas shielded arc welding, wherein the welding current is switched to at least a current non-suppression period T based on at least a front end position or a feed speed signal of the welding wire. IP Or the current suppression period T IB The feed and welding current control is performed so that during the forward feed period T P and reverse feed period T N The welding wire is fed toward the base material during the periodic switching of these periods.

[0382] The additive manufacturing method is characterized in that

[0383] If there is one or more cycles including an arc period and a short circuit period within a predetermined time,

[0384] The welding conditions are set or corrected so that the ratio of the short-circuit period to the predetermined time becomes equal to or less than the value of the following formula (1) related to the feed speed setting value FW.

[0385] 0.007×FW+0.249 ・・・Formula (1)

[0386] According to this structure, in an additive manufacturing method of gas metal arc welding that applies an arc welding method in which forward feeding and reverse feeding of the front end of the welding wire are periodically repeated, an excellent weld bead shape and optimal penetration performance corresponding to the conditions can be obtained regardless of the welding speed.

[0387] Various embodiments have been described above, but the present invention is certainly not limited to this example. It should be understood by those skilled in the art that various variations or modifications can be thought of within the scope described in the claims, and they certainly also belong to the technical scope of the present invention. In addition, the various structural elements in the above-mentioned embodiments may also be arbitrarily combined within the scope of the gist of the invention.

[0388] In addition, this application is based on the Japanese patent application (Japanese Patent Application No. 2022-080526) filed on May 16, 2022, and the contents are incorporated herein by reference.

[0389] -Description of Reference Numerals-

[0390] 50 Welding System

[0391] 100 Welding wire

[0392] 120 Welding control device (robot control device)

[0393] 140 Welding Power Supply

[0394] d Depth of penetration

[0395] f Frequency

[0396] h weld bead height

[0397] I Average welding current

[0398] I P1 Welding current setting value

[0399] I P2 Welding current setting value

[0400] T C Current control range

[0401] Tf period

[0402] T IB Current suppression period

[0403] T IP Current non-suppression period

[0404] T N During reverse feed

[0405] T P During forward feed

[0406] w Weld bead width

[0407] Wf amplitude.

Claims

1. A method for controlling gas metal arc welding, in which a shielding gas containing 30% or more of CO2 is used and a thin plate is used as a welding material. Based on at least the tip position of the welding wire or the feed speed signal, the welding current is switched to at least the current non-suppression period T IP Or the current suppression period T IB The feed and welding current control is performed so that during the forward feed period T P and reverse feed period T N The welding wire is fed toward the base material during the periodic switching of these periods. The control method of the metal-electrode gas shielded arc welding is characterized by comprising: a short circuit time ratio determining step of determining a ratio of the short circuit period to the predetermined time when there is one or more cycles including an arc period and a short circuit period within the predetermined time; and The welding condition determination step sets or corrects welding conditions so that the ratio of the short circuit period determined in the short circuit time ratio determination step becomes at least a predetermined threshold value or a calculated threshold value, or a predetermined target value or a calculated target value.

2. The method for controlling gas metal arc welding according to claim 1, characterized in that: The method comprises the step of determining the threshold value or the target value based on a predetermined item of welding information, The item of the welding information is selected from at least one of a welding wire type, a gas composition, a welding wire diameter, a plate thickness, a feed speed setting value FW, and a welding speed.

3. The control method of metal-electrode gas shielded arc welding according to claim 2, characterized in that: When determining the threshold value, the threshold value is calculated based on at least the following formula (1) related to the feed speed setting value FW: 0.007×FW+0.249 …………Formula (1).

4. The method for controlling gas metal arc welding according to any one of claims 1 to 3, characterized in that: In the welding condition determination step, As the welding condition items, at least the frequency f of the one cycle, the amplitude Wf ​​of the forward feed or reverse feed of the welding wire, the welding current, and the arc voltage are set. In the case of high-speed welding with a welding speed of 80 cm / min or more, The welding conditions are set or modified so that the set value or the detected value of the frequency f, the amplitude Wf, the welding current and the arc voltage satisfies the following formula (2): (Arc voltage) / (Welding current) ≥ 0.0237×(Frequency / Amplitude)-0.376 ……Formula (2).

5. The method for controlling metal-electrode gas shielded arc welding according to claim 4, characterized in that: The welding conditions are set or modified so that: The setting value or detection value of the frequency f is in the range of 50 to 150, The setting value or detection value of the amplitude Wf ​​is in the range of 3.0 to 8.75, and The frequency f / the amplitude Wf ​​satisfies 10-25.

6. The method for controlling metal-electrode gas shielded arc welding according to claim 4, characterized in that: The set value or the detected value of the welding current or the arc voltage uses an average value, respectively, and the welding condition is set or corrected so that (arc voltage) / (welding current) satisfies 0.05V to 20V / 100A.

7. The method for controlling gas metal arc welding according to any one of claims 1 to 3, characterized in that: In the welding condition determination step, As the welding condition to be set or modified, During the current non-suppression period T IP There are at least two welding current setting values ​​I P1 ,I P2 , During the forward feed period T P In the example, the position of the welding wire at which the feed speed is set is set to 0 degrees. In this case, Set or modify the welding current setting value I within the range of 20 degrees or less P1 The end position of the range, Set or modify the welding current setting value I within the range of 135 to 220 degrees P2 The end position of the range.

8. The method for controlling gas metal arc welding according to claim 7, characterized in that: As the welding condition to be set or modified, When the welding current is set to I P2 The end of the range is set as the current non-suppression period T IP terminal, set the welding current to I P2 When the end position of the range is set to Xdeg, The current suppression period T is set or modified within the range of (X+100) to (X+220) degrees. IB terminal position.

9. The method for controlling gas metal arc welding according to claim 7, characterized in that: The welding current setting value I P1 The setting current is set to 300-600A, and the welding current setting value I P1 The setting voltage is set to 20~45V, The welding current setting value I P2 The setting current is set to 350-650A, and the welding current setting value I P2 The set voltage is set to 20~50V.

10. The method for controlling gas metal arc welding according to any one of claims 1 to 3, characterized in that: Regarding the feed and welding current control, control is performed so that the current non-suppression period T IP The forward feed period T P for more than 2 / 3 of the period.

11. The method for controlling gas metal arc welding according to any one of claims 1 to 3, characterized in that: A database is provided, wherein for each item of welding information selected from at least one of welding wire type, gas composition, welding wire diameter, plate thickness, feed speed setting value, and welding speed, the ratio of the short circuit period is associated with the item of the welding condition, In the welding condition determination step, the welding condition is determined based on the items of the welding information input in advance and the database, and the welding condition is set or corrected.

12. The method for controlling gas metal arc welding according to claim 11, characterized in that: The welding condition items include at least one of the following items: The forward feeding period T of the welding wire P and reverse feed period T N Set the frequency f to 1 cycle; The amplitude Wf ​​of the welding wire during forward feeding or reverse feeding; The current non-suppression period T IP The welding current setting value; The current non-suppression period T IP Arc voltage setting value; The current suppression period T IB The welding current setting value; The current suppression period T IB Arc voltage setting value; End the current non-suppression period T IP The welding wire position information (Deg5); welding wire position information (Deg Ta1) at the end of the current suppression period; and The forward feeding period T P During the reverse feed period T N ratio (PFR).

13. The method for controlling gas metal arc welding according to claim 11, characterized in that: The method comprises at least detecting arc voltage during welding, In the short circuit time ratio determination step, based on the detected value of the arc voltage, a period during which the voltage is equal to or less than a predetermined voltage value is calculated as the short circuit period, and based on the calculated short circuit period, the short circuit time ratio is determined. In the welding condition determination step, the welding condition is corrected so that the short circuit time ratio becomes at least a predetermined threshold value or a calculated threshold value or a predetermined target value or a calculated target value.

14. The method for controlling gas metal arc welding according to claim 12, characterized in that: The method comprises at least detecting arc voltage during welding, In the short circuit time ratio determination step, based on the detected value of the arc voltage, a period during which the voltage is equal to or less than a predetermined voltage value is calculated as the short circuit period, and based on the calculated short circuit period, the short circuit time ratio is determined. In the welding condition determination step, the welding condition is corrected so that the short circuit time ratio becomes at least a predetermined threshold value or a calculated threshold value or a predetermined target value or a calculated target value.

15. A method for setting welding conditions in gas metal arc welding using a shielding gas containing 30% or more of CO2 and using a thin plate as a welding material, The method for setting welding conditions is for switching the welding current to at least the current non-suppression period T based on at least the tip position of the welding wire or the feed speed signal. IP Or the current suppression period T IB The feed and welding current control is performed so that during the forward feed period T P and reverse feed period T N The welding wire is fed toward the base material during the periodic switching of these periods. The method for setting welding conditions is characterized in that: If there is one or more cycles including an arc period and a short circuit period within a predetermined time, determining a ratio of the short circuit period to the predetermined time, The welding conditions are set so that the determined ratio of the short-circuit period becomes at least a predetermined threshold value or a calculated threshold value or a predetermined target value or a calculated target value.

16. A welding control device, in gas metal arc welding when a shielding gas containing 30% or more of CO2 is used and a thin plate is used as a welding material, The welding control device is used to switch the welding current to at least the current non-suppression period T based on at least the tip position of the welding wire or the feed speed signal. IP Or the current suppression period T IB The feed and welding current control is performed so that during the forward feed period T P and reverse feed period T N The welding wire is fed toward the base material during the periodic switching of these periods. The welding control device is characterized by having: a short circuit time ratio determination unit that determines a ratio of the short circuit period to the predetermined time when there are one or more cycles including an arc period and a short circuit period within the predetermined time; and The welding condition determination unit sets or corrects welding conditions so that the ratio of the short circuit period determined by the short circuit time ratio determination unit becomes at least a predetermined threshold value or a calculated threshold value, or a predetermined target value or a calculated target value.

17. A welding power source, wherein: A welding control device according to claim 16 is provided.

18. A welding system, wherein: A welding power source according to claim 17 is provided.

19. A procedure for performing metal-electrode gas shielded arc welding using a shielding gas containing 30% or more of CO2 and using a thin plate as a material to be welded. The welding control device is used to switch the welding current to at least the current non-suppression period T based on at least the tip position of the welding wire or the feed speed signal. IP Or the current suppression period T IB The feed and welding current control is performed so that during the forward feed period T P and reverse feed period T N The welding wire is fed toward the base material during the periodic switching of these periods. It is characterized in that A computer of a welding system having at least the welding control device is caused to execute a function having the following steps: a short circuit time ratio determination step, in which, when there is one or more cycles including an arc period and a short circuit period within a predetermined time, the welding control device determines a ratio of the short circuit period to the predetermined time; as well as The welding control device sets or corrects welding conditions so that the ratio of the short circuit period determined in the short circuit time ratio determination step becomes at least a predetermined threshold value or a calculated threshold value, or a predetermined target value or a calculated target value.

20. A method of gas metal arc welding, comprising: using a shielding gas containing 30% or more of CO2 and using a thin plate as a welding material; A control method for metal-electrode gas shielded arc welding is adopted, wherein the welding current is switched to at least a current non-suppression period T based on at least the front end position or feed speed signal of the welding wire. IP Or the current suppression period T IB The feed and welding current control is performed so that during the forward feed period T P and reverse feed period T N The welding wire is fed toward the base material during the periodic switching of these periods. The gas metal arc welding method is characterized in that: If there is one or more cycles including an arc period and a short circuit period within a predetermined time, The welding conditions are set or corrected so that the ratio of the short circuit period to the predetermined time becomes equal to or less than the value of the following formula (1) related to the feed speed setting value FW. 0.007×FW+0.249 …………Formula (1).

21. An additive manufacturing method, which employs metal-electrode gas-shielded arc welding using a shielding gas containing 30% or more of CO2 and a thin plate as a welded material, A control method for metal-electrode gas shielded arc welding is adopted, wherein the welding current is switched to at least a current non-suppression period T based on at least the front end position or feed speed signal of the welding wire. IP Or the current suppression period T IB The feed and welding current control is performed so that during the forward feed period T P and reverse feed period T N The welding wire is fed toward the base material during the periodic switching of these periods. The additive manufacturing method is characterized in that If there is one or more cycles including an arc period and a short circuit period within a predetermined time, The welding conditions are set or corrected so that the ratio of the short circuit period to the predetermined time becomes equal to or less than the value of the following formula (1) related to the feed speed setting value FW. 0.007×FW+0.249 …………Formula (1).

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